Ozone Increasing Greenhouse Effect What is ozone? Ozone is a molecule made up of three atoms of oxygen. It works a lot like sunscreen, blocking out harmful ultraviolet (UV) rays from the sun. In recent years, the amount of ozone in the atmosphere has decreased. So will the Earth, and all of the life on it, get sunburned? That�s the concern, and it�s one of the reasons why ozone is being looked at a lot by scientists who study climate and changes in Earth systems. Is ozone good or bad? That�s a trick question, because the answer is: It depends. Most ozone is found below a 30 mile (48 km) height. However, depending upon WHERE the ozone is located, it can protect or harm life. Where is good and bad ozone located? Click the image below to open the Interactive Atmosphere to see where the different parts of the atmosphere are located. The atmosphere is really a thin layer of gases surrounding the Earth. How thin? Well, imagine a basketball with one layer of aluminum foil around it. The aluminum foil represents the average thickness of the atmosphere. That�s pretty thin!

And considering without an atmosphere we�d all die, it�s kind of important to take care of the atmosphere. The different layers of the atmosphere The atmosphere is divided into regions defined primarily by temperature. The height and temperature of these layers can vary from season to season. From the Earth�s surface through the bottom layer of atmosphere, called the troposphere, temperature decreases with altitude. Weather occurs in this layer. It�s also the layer we live in. The next layer up is called the stratosphere. In the stratosphere, temperature increases with altitude. This is because of ozone. When the ozone in this layer absorbs UV light from the sun, it increases in temperature. In the mesosphere, ozone concentration decreases. This means there is less absorption of UV light in this layer of atmosphere. Do you think the temperature would increase or decrease In this layer of the atmosphere? In the upper atmosphere, called the thermosphere, temperatures are HOT. This is because incoming energy from the sun heats the molecules up. Are you wondering about the increase in temperature within the thermosphere? Well, this occurs because short-wave, high-energy solar radiation is absorbed by the (relatively few) molecules of oxygen and nitrogen.

Since temperature is defined as speed of molecules, the temperature is very hot. However, since there are few molecules to transfer the heat, it would not feel hot to you because the "air" is so thin. So where is ozone "good", and where is it "bad" for life? High in the stratosphere, ozone acts as a protection from UV light. Without this protective shield, all animal life (not just humans) would be more susceptible to cancer, impaired immune systems, and eye problems like cataracts. If the ozone is close to the Earth and we breathe it in, ozone can damage our lungs. As well as harming animals, ozone also impairs the transpiration (breathing) process in plants. The amount of "good" and "bad" ozone in the atmosphere depends upon the balance between the processes that make ozone and those that destroy ozone. An upset in this balance could have serious consequences for all types of life on Earth.

Ozone in the Troposphere Ozone in the troposphere is "bad" for breathing, for contributing to the smog and greenhouse gases created by human activities, and it can also act as a chemical oxidant by ripping off oxygen atoms from other compounds (including you, the plants around you, other animals, etc.)! Ozone this close to the surface does not exist in high enough concentrations to shield us from UV light at this level, so its benefits are only truly seen in the stratosphere. Ozone in the Stratosphere Science - Ozone Basics Where is ozone found in the atmosphere? Ozone is mainly found in two regions of the Earth's atmosphere. Most ozone (about 90%) resides in a layer that begins between 6 and 10 miles (10 and 17 kilometers) above the Earth's surface and extends up to about 30 miles (50 kilometers). This region of the atmosphere is called the stratosphere. The ozone in this region is commonly known as the ozone layer. The remaining ozone is in the lower region of the atmosphere, which is commonly called the troposphere. The figure (above) shows an example of how ozone is distributed in the atmosphere.

What roles does ozone play in the atmosphere and how are humans affected? The ozone molecules in the upper atmosphere (stratosphere) and the lower atmosphere (troposphere) are chemically identical, because they all consist of three oxygen atoms and have the chemical formula O3. However, they have very different roles in the atmosphere and very different effects on humans and other living beings. Stratospheric ozone (sometimes referred to as "good ozone") plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface. The absorption of ultraviolet radiation by ozone creates a source of heat, which actually forms the stratosphere itself (a region in which the temperature rises as one goes to higher altitudes). Ozone thus plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface. Many experimental studies of plants and animals and clinical studies of humans have shown the harmful effects of excessive exposure to UV-B radiation.

At the Earth's surface, ozone comes into direct contact with life-forms and displays its destructive side (hence, it is often called "bad ozone"). Because ozone reacts strongly with other molecules, high levels of ozone are toxic to living systems. Several studies have documented the harmful effects of ozone on crop production, forest growth, and human health. The substantial negative effects of surface-level tropospheric ozone from this direct toxicity contrast with the benefits of the additional filtering of UV-B radiation that it provides. What are the environmental issues associated with ozone? The dual role of ozone leads to two separate environmental issues. There is concern about increases in ozone in the troposphere. Near-surface ozone is a key component of photochemical "smog," a familiar problem in the atmosphere of many cities around the world. Higher amounts of surface-level ozone are increasingly being observed in rural areas as well. There is also widespread scientific and public interest and concern about losses of ozone in the stratosphere. Ground-based and satellite instruments have measured decreases in the amount of stratospheric ozone in our atmosphere. Over some parts of Antarctica, up to 60% of the total overhead amount of ozone (known as the column ozone) is depleted during Antarctic spring (September-November).

This phenomenon is known as the Antarctic ozone hole. In the Arctic polar regions, similar processes occur that have also led to significant chemical depletion of the column ozone during late winter and spring in 7 out of the last 11 years. The ozone loss from January through late March has been typically 20-25%, and shorter-period losses have been higher, depending on the meteorological conditions encountered in the Arctic stratosphere. Smaller, but still significant, stratospheric decreases have been seen at other, more-populated regions of the Earth. Increases in surface UV-B radiation have been observed in association with local decreases in stratospheric ozone, from both ground-based and satellite-borne instruments. What human activities affect upper-atmospheric ozone (the stratospheric ozone layer)? The scientific evidence, accumulated over more than two decades of study by the international research community, has shown that human-produced chemicals are responsible for the observed depletions of the ozone layer. The ozone-depleting compounds contain various combinations of the chemical elements chlorine, fluorine, bromine, carbon, and hydrogen and are often described by the general term halocarbons.

The compounds that contain only chlorine, fluorine, and carbon are called chlorofluorocarbons, usually abbreviated as CFCs. CFCs, carbon tetrachloride, and methyl chloroform are important human-produced ozone-depleting gases that have been used in many applications including refrigeration, air conditioning, foam blowing, cleaning of electronics components, and as solvents. Another important group of human-produced halocarbons is the halons, which contain carbon, bromine, fluorine, and (in some cases) chlorine and have been mainly used as fire extinguishants. What actions have been taken to protect the ozone layer? Through an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer, governments have decided to eventually discontinue production of CFCs, halons, carbon tetrachloride, and methyl chloroform (except for a few special uses), and industry has developed more "ozone-friendly" substitutes. All other things being equal, and with adherence to the international agreements, the ozone layer is expected to recover over the next 50 years or so.

* Text and figure are adapted from the Introduction to "Frequently Asked Questions" of the World Meteorological Organization/United Nations Environment Programme report, Scientific Assessment of Ozone Depletion: 1998 (WMO Global Ozone Research and Monitoring Project-Report No. 44, Geneva, 1999). The Layers of Earth's Atmosphere the thermosphere, and the exosphere. In-between each of these major five layers are transition zones called "pauses" where temperature changes, air composition, and air density occur. Pauses included, the atmosphere is a total of 9 layers thick! The Troposphere: Where Weather Happens Of all the atmosphere's layer's, the troposphere is the one we're most familiar with (whether you realize it or not) since we live at it's bottom -- the Earth's surface. It hugs the Earth's surface and extends upward to about high. Troposphere means, ‘where the air turns over’. A very appropriate name, since it is the layer where our day-to-day weather takes place.

continue reading below our video What are the Seven Wonders of the World Starting at sea level, the troposphere goes up 4 to 12 miles (6 to 20 km) high. The bottom one third, that which is closest to us, contains 50% of all atmospheric gases. This is the only part of the whole makeup of the atmosphere that is breathable. Thanks to its air being heated from below by the earth's surface which absorbs the sun's heat energy, tropospheric temperatures decrease as you travel up into the layer. At its top is a thin layer called the tropopause, which is just a buffer between the troposphere and the stratosphere. The Stratosphere: Ozone's Home The stratosphere is the next layer of the atmosphere. It extends anywhere from 4 to 12 miles (6 to 20 km) above Earth's surface up to 31 miles (50 km). This is the layer where most commercial airliners fly and weather balloons travel to. Here the air doesn’t flow up and down, but flows parallel to the earth in very fast moving air streams .

It's temperature also increases as you go up, thanks to the abundance of natural ozone (O3) -- the byproduct of solar radiation and oxygen which has a knack for absorbing the sun's harmful UV rays. (Anytime temperatures increase with elevation in meteorology, it's known as an "inversion.") Since the stratosphere has warmer temperatures at its bottom and cooler air at its top, convection (thunderstorms) is rare in this part of the atmosphere. In fact, you can visibly spot its bottom layer in stormy weather by where the anvil-shaped tops of cumulonimbus clouds are. How so? Since the layer acts as a "cap" to convection, the tops of storm clouds have nowhere to go but spread outward. After the stratosphere, there is again a buffer layer, this time called the stratopause. The Mesosphere: The "Middle Atmosphere" Starting roughly 31 miles (50 km) above Earth's surface and extending up to 53 miles (85 km) is the mesosphere. The mesosphere's top region is the coldest naturally occurring place on Earth.

Its temperatures can dip below -220 °F (-143 °C, -130 K)! The Thermosphere: The "Upper Atmosphere" After the mesosphere and mesopause comes the thermosphere. Measured between 53 miles (85 km) and 375 miles (600 km) above earth, it contains less than 0.01% of all air within the atmospheric envelope. Temperatures here reach upward to 3,600 °F (2,000 °C), but because the air is so thin and there are so few gas molecules to transfer the heat, these high temperatures would amazingly feel very cold to our skin. The Exosphere: Where Atmosphere and Outer Space Meet Some 6,200 miles (10,000 km) above the earth is the exosphere -- the atmosphere's outer edge. It is where weather satellites orbit the earth. What about the Ionosphere? The ionosphere isn't its own separate layer, but is actually the name given to the atmosphere from about 37 miles (60 km) to 620 miles (1,000 km) high.

(It includes the top-most parts of the mesosphere and all of the thermosphere and exosphere.) Gas atoms drift into space from here. It is called ionosphere because in this part of the atmosphere the sun’s radiation is ionized, or pulled apart as it travels earth’s magnetic fields to the north and south poles. This pulling apart is seen from earth as auroras . Contributed in part by Sharon Tomlinson ozone layer - National Geographic Society ozone layer The amount of ozone in the atmosphere is measured in "Dobson units." Photograph by Suzailan Shoroyo, MyShot Million to One Compared to other gases in the atmosphere, ozone is pretty rare. According to NOAA, there are only about three molecules of ozone for every ten million molecules of air. The ozone layer is one layer of the stratosphere , the second layer of the Earth’s atmosphere . The stratosphere is the mass of protective gases cling ing to our planet. The stratosphere gets its name because it is stratified, or layered: as elevation increases, the stratosphere gets warmer. The stratosphere increases in warmth with elevation because ozone gas es in the upper layers absorb intense ultraviolet radiation from the sun.

Ozone is only a trace gas in the atmosphere—only about 3 molecule s for every 10 million molecules of air. But it does a very important job. Like a sponge , the ozone layer absorbs bits of radiation hitting Earth from the sun. Even though we need some of the sun's radiation to live, too much of it can damage living things. The ozone layer acts as a shield for life on Earth. Ozone is good at trapping a type of radiation called ultraviolet radiation, or UV light, which can penetrate organisms’ protective layers, like skin , damaging DNA molecules in plants and animals. There are two major types of UV light: UVB and UVA. UVB is the cause of skin conditions like sunburns, and cancer s like basal cell carcinoma and squamous cell carcinoma. People used to think that UVA light, the radiation used in tanning beds, is harmless because it doesn’t cause burns. However, scientists now know that UVA light is even more harmful than UVB, penetrating more deeply and causing a deadly skin cancer, melanoma , and premature aging. The ozone layer, our Earth’s sunscreen, absorbs about 98 percent of this devastating UV light. The ozone layer is getting thinner.

Chemicals called chlorofluorocarbons (CFCs) are a reason we have a thinning ozone layer. A chlorofluorocarbon (CFC) is a molecule that contains the element s carbon, chlorine, and fluorine. CFCs are everywhere, mostly in refrigerant s and plastic products. Businesses and consumer s use them because they're inexpensive, they don't catch fire easily, and they don't usually poison living things. But the CFCs start eating away at the ozone layer once they get blown into the stratosphere. Ozone molecules, which are simply made of three joined oxygen atoms, are always being destroyed and reformed naturally. But CFCs in the air make it very difficult for ozone to reform once it’s broken apart. The ozone layer, which only makes up 0.00006 percent of Earth’s atmosphere, is getting thinner and thinner all the time. “ Ozone hole s” are popular names for areas of damage to the ozone layer. This is inaccurate . Ozone layer damage is more like a really thin patch than a hole. The ozone layer is thinnest near the pole s.

In the 1970s, people all over the world started realizing that the ozone layer was getting thinner and that this was a bad thing. Many government s and businesses agreed that some chemicals, like aerosol can s, should be outlaw ed. There are fewer aerosol cans produced today. The ozone layer has slowly recovered as people, businesses, and governments work to control such pollution . Term aerosol can Noun container of liquid material under high pressure. When released through a small opening, the liquid becomes a spray or foam. atmosphere growth of abnormal cells in the body. chlorofluorocarbon (CFC) Noun chemical compound mostly used in refrigerants and flame-retardants. Some CFCs have destructive effects on the ozone layer. cling to attach or stick to. consumer person who uses a good or service. damage harm that reduces usefulness or value. devastate (deoxyribonucleic acid) molecule in every living organism that contains specific genetic information on that organism. element chemical that cannot be separated into simpler substances. elevation gas Noun state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion.

government system or order of a nation, state, or other political unit. inaccurate dangerous and sometimes fatal skin cancer. molecule smallest physical unit of a substance, consisting of two or more atoms linked together. outlaw to make illegal or against the law. oxygen chemical element with the symbol O, whose gas form is 21% of the Earth's atmosphere. ozone hole Noun circular pattern, usually located near the Antarctic, of thin atmospheric ozone, which absorbs harmful ultraviolet sunlight. ozone layer Noun chemical material that can be easily shaped when heated to a high temperature. poison extreme north or south point of the Earth's axis. pollution energy, emitted as waves or particles, radiating outward from a source. refrigerant substance used to keep materials cool. skin soft external covering of some animals. sponge substance that easily absorbs other material. stratify stratosphere Noun level of Earth's atmosphere, extending from 10 kilometers (6 miles) to 50 kilometers (31 miles) above the surface of the Earth. ultraviolet radiation Noun powerful light waves that are too short for humans to see, but can penetrate Earth's atmosphere. Ultraviolet is often shortened to UV.

UVB Noun type of ultraviolet (UV) radiation that can cause sunburn, skin cancer, and types of eye damage. volcanic eruption The Ozone Layer The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone (O3). This layer absorbs 97-99% of the sun's high frequency ultraviolet light, which is potentially damaging to life on earth. Over 90% of ozone in earth's atmosphere is present here "Relatively high" means a few parts per million—much higher than the concentrations in the lower atmosphere but still small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from approximately 15 km to 35 km above Earth's surface, though the thickness varies seasonally and geographically. A dobson unit is the most basic measure used in ozone research.One Dobson Unit (DU) is defined to be 0.01 mm thickness at STP (standard temperature and pressure). Ozone layer thickness is expressed in terms of Dobson units, which measure what its physical thickness would be if compressed in the Earth's atmosphere. In those terms, it's very thin indeed.

A normal range is 300 to 500 Dobson units, which translates to an eighth of an inch-basically two stacked pennies. In space, it's best not to envision the ozone layer as a distinct, measurable band. Instead, think of it in terms of parts per million concentrations in the stratosphere (the layer six to 30 miles above the Earth's surface). The unit is named after G.M.B. Dobson, one of the first scientists to investigate atmospheric ozone . A thinning ozone layer leads to a number of serious health risks for humans. It causes greater incidences of skin cancer and cataract of the eye, with children being particularly vulnerable. There are also serious impacts for biodiversity. Increased UV-B rays reduce levels of plankton in the oceans and subsequently diminish fish stocks. It can also have adverse effects on plant growth, thus reducing agricultural productivity. Another negative effect is the reduced lifespan of certain materials. Severe depletion of the Antarctic ozone layer was first observed in the early 1980s. The international response embodied in the Montreal Protocol.

Today 191 countries worldwide have signed the Montreal Protocol which is widely regarded as the most successful Multinational Environmental Agreement ever reached to date. Furthermore the phasing out of ozone depleting substances (ODS) has helped to fight climate change since many ODS are also powerful greenhouse gases. The Stratosphere - overview | UCAR Center for Science Education The Stratosphere - overview This diagram shows some of the features of the stratosphere. Credit: Randy Russell, UCAR The stratosphere is a layer of Earth's atmosphere. It is the second layer of the atmosphere as you go upward. The troposphere , the lowest layer, is right below the stratosphere. The next higher layer above the stratosphere is the mesosphere . The bottom of the stratosphere is around 10 km (6.2 miles or about 33,000 feet) above the ground at middle latitudes. The top of the stratosphere occurs at an altitude of 50 km (31 miles). The height of the bottom of the stratosphere varies with latitude and with the seasons.

The lower boundary of the stratosphere can be as high as 20 km (12 miles or 65,000 feet) near the equator and as low as 7 km (4 miles or 23,000 feet) at the poles in winter. The lower boundary of the stratosphere is called the tropopause; the upper boundary is called the stratopause. Ozone, an unusual type of oxygen molecule that is relatively abundant in the stratosphere, heats this layer as it absorbs energy from incoming ultraviolet radiation from the Sun. Temperatures rise as one moves upward through the stratosphere. This is exactly the opposite of the behavior in the troposphere in which we live, where temperatures drop with increasing altitude. Because of this temperature stratification, there is little convection and mixing in the stratosphere, so the layers of air there are quite stable. Commercial jet aircraft fly in the lower stratosphere to avoid the turbulence which is common in the troposphere below. The stratosphere is very dry; air there contains little water vapor. Because of this, few clouds are found in this layer; almost all clouds occur in the lower, more humid troposphere.

Polar stratospheric clouds (PSCs) are the exception. PSCs appear in the lower stratosphere near the poles in winter. They are found at altitudes of 15 to 25 km (9.3 to 15.5 miles) and form only when temperatures at those heights dip below -78° C. They appear to help cause the formation of the infamous holes in the ozone layer by "encouraging" certain chemical reactions that destroy ozone. PSCs are also called nacreous clouds. Air is roughly a thousand times thinner at the top of the stratosphere than it is at sea level. Because of this, jet aircraft and weather balloons reach their maximum operational altitudes within the stratosphere. Due to the lack of vertical convection in the stratosphere, materials that get into the stratosphere can stay there for long times. Such is the case for the ozone-destroying chemicals called CFCs (chlorofluorocarbons). Large volcanic eruptions and major meteorite impacts can fling aerosol particles up into the stratosphere where they may linger for months or years, sometimes altering Earth's global climate.

Rocket launches inject exhaust gases into the stratosphere, producing uncertain consequences. Various types of waves and tides in the atmosphere influence the stratosphere. Some of these waves and tides carry energy from the troposphere upward into the stratosphere; others convey energy from the stratosphere up into the mesosphere. The waves and tides influence the flows of air in the stratosphere and can also cause regional heating of this layer of the atmosphere. A rare type of electrical discharge, somewhat akin to lightning, occurs in the stratosphere. These "blue jets" appear above thunderstorms, and extend from the bottom of the stratosphere up to altitudes of 40 or 50 km (25 to 31 miles). © 2011 UCAR with portions adapted from Windows to the Universe (© 2009 NESTA) Basic Ozone Layer Science | Ozone Layer Protection | US EPA Basic Ozone Layer Science I. The Ozone Layer The Earth's atmosphere is composed of several layers.

The lowest layer, the troposphere Addressing Ozone Layer Depletion Most atmospheric ozone is concentrated in a layer in the stratosphere, about 9 to 18 miles (15 to 30 km) above the Earth's surface (see the figure below). Ozone is a molecule that contains three oxygen atoms. At any given time, ozone molecules are constantly formed and destroyed in the stratosphere. The total amount has remained relatively stable during the decades that it has been measured. UVBA band of ultraviolet radiation with wavelengths from 280-320 nanometers produced by the Sun. UVB is a kind of ultraviolet light from the sun (and sun lamps) that has several harmful effects. UVB is particularly effective at damaging DNA. It is a cause of melanoma and other types of skin cancer. It has also been linked to damage to some materials, crops, and marine organisms. The ozone layer protects the Earth against most UVB coming from the sun. It is always important to protect oneself against UVB, even in the absence of ozone depletion, by wearing hats, sunglasses, and sunscreen. However, these precautions will become more important as ozone depletion worsens. NASA provides more information on their web site ( .

UVB has been linked to many harmful effects , including skin cancers, cataracts, and harm to some crops and marine life. Scientists have established records spanning several decades that detail normal ozone levels during natural cycles. Ozone concentrations in the atmosphere vary naturally with sunspots, seasons, and latitude. These processes are well understood and predictable. Each natural reduction in ozone levels has been followed by a recovery. Beginning in the 1970s, however, scientific evidence showed that the ozone shield was being depleted well beyond natural processes. Additional Information Health and Environmental Effects of Ozone Depletion II. Ozone Depletion When chlorine and bromine atoms come into contact with ozone in the stratosphere, they destroy ozone molecules. One chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere. Ozone can be destroyed more quickly than it is naturally created. Some compounds release chlorine or bromine when they are exposed to intense UV light in the stratosphere. These compounds contribute to ozone depletion, and are called ozone-depleting substances ( ODS methyl bromideA compound consisting of carbon, hydrogen, and bromine.

Methyl Bromide is an effective pesticide used to fumigate soil and many agricultural products. Because it contains bromine, it depletes stratospheric ozone and has an ozone depletion potential of 0.6. Production of methyl bromide was phased out on December 31, 2004, except for allowable exemptions. Much more information is available ( . Although ODS are emitted at the Earth’s surface, they are eventually carried into the stratosphere in a process that can take as long as two to five years. In the 1970s, concerns about the effects of ozone-depleting substances ( ODS NASA - The Good, the Bad and the Ozone The Good, the Bad and the Ozone 06.04.04 Ozone is a big buzz word these days. We mostly hear about the ozone layer, and the importance of protecting it. But if you want to understand what ozone's all about, you need to understand that it can be good, and it can be bad. + The good kind of ozone The stratosphere is the layer of the atmosphere from 10 to 30 miles above sea level.

When there's ozone in this layer, it protects us from solar radiation. How? Simple chemistry. Regular oxygen molecules, known to science-types as O2, are made up of two oxygen atoms stuck together. Solar energy shoots in from space and splits that molecule into two atoms. When one of those stray atoms attaches to a full-fledged O2 molecule, you've got, well, O3, otherwise known as ozone. All that action blocks solar radiation, and keeps it from reaching us. Image above: The second largest ozone hole ever observed is seen above Antarctica in this image from September 2003. Credit: NASA How can solar radiation be harmful to life on Earth? Part of that radiation is ultra-violet, or UV radiation. It's an intense energy from the Sun that can cause a whole lot of damage. Skin cancer is the most dramatic result of a too much UV radiation, but there's a lot more too. Photosynthesis in plants is also affected, and that causes problems for the whole food chain. See where this is headed? We need to protect our ozone shield, and we can do so by decreasing the pollution that our industrial society puts out in large amounts every day.

+ The bad kind of ozone Let's come down a little closer to Earth. The troposphere is everything below the stratosphere, from sea level to about 10 miles above. It's where everything lives. Things that happen to the troposphere happen to us; there's nothing indirect about it. Put a little ozone in the troposphere and you've got some big problems. Remember those dramatic chemical reactions that happened up in the stratosphere? Living things are made of atoms and molecules too, so when we expose them to ozone, we've got some serious chemical reactions on our hands. Image above: Parts of the Los Angeles area are considered to contain unhealthy amounts of ground level ozone. Red areas on the map indicate more than 100 parts per billion by volume of the molecule. Credit: EPA In humans, it means lung damage. Small children and people with asthma are especially at risk. How can you help solve the problem? Cars, trucks and SUVs are the biggest contributor to this ozone buildup. Engine exhaust creates nitrogen dioxide, so the more you drive, the more your vehicle creates. High gas prices aren't the only reason to leave the car in the garage. + So what now? Did you know?

The launch of Aura will culminate a 15-year international effort to establish the world's most comprehensive Earth Observing System, which aims to determine the extent, causes, and regional consequences of global change. NASA's Aura is going to keep tabs on both types of ozone. It's a spacecraft that will provide us the first comprehensive global view of the Earth's atmosphere, an essential stepping stone to better understanding the Moon, Mars and beyond. The launch of Aura is a challenging endeavor, a mission on the cutting edge of scientific discovery characteristic of the Agency's legacy of ground-breaking exploration. One of its most impressive tools is the Ozone Monitoring Instrument, or OMI. The device will measure the amount of energy going into and coming out of the Earth, in a technique known as the "backscatter" method. The results of these observations will tell scientists how much ozone is over a particular area, and how much the area is gaining or losing over time. Aura is a complex mission for a complex problem; but simply put, it's critical to understanding and protecting the air we breathe.

Current State of the Ozone Layer | Ozone Layer Protection | US EPA Current State of the Ozone Layer Key Resource EPA Achievements in Stratospheric Ozone Protection Atmospheric levels of ozone-depleting substances ( ODS Addressing Ozone Layer Depletion Continued declines in ODS emissions are expected to result in a near complete recovery of the ozone layer near the middle of the 21st century. The long time scale for this recovery is due to the slow rate at which ODS are removed from the atmosphere by natural processes. Many organizations monitor the status of the ozone layer: Scientific Assessment of Ozone Depletion: 2014 Exit This is the most recent World Meteorological Organization (WMO) and United Nations Environmental Programme (UNEP) assessment. It contains the most up-to-date understanding of ozone depletion and reflects the thinking of over 312 international scientific experts who contributed to its preparation and review. A related document provides Questions and Answers about the Ozone Layer: 2014 Update . Exit Atmosphere A planet's climate is decided by its mass, its distance from the sun and the composition of its atmosphere. Earth's atmosphere is 78% nitrogen, 21% oxygen, and 1% other gases.

Carbon dioxide accounts for just 0.03 - 0.04%. Water vapour, varying in amount from 0 to 2%, carbon dioxide and some other minor gases present in the atmosphere absorb some of the thermal radiation leaving the surface and emit radiation from much higher and colder levels out to space. These radiatively active gases are known as greenhouse gases because they act as a partial blanket for the thermal radiation from the surface and enable it to be substantially warmer than it would otherwise be, analogous to the effect of a greenhouse. This blanketing is known as the natural greenhouse effect. Without the greenhouse gases, Earth's average temperature would be roughly -20°C. T The atmosphere is a cloud of gas and suspended solids extending from the Earth's surface out many thousands of miles, becoming increasingly thinner with distance but always held by the Earth's gravitational pull. The atmosphere is made up of layers. it surrounds the Earth and holds the air we breathe; it protects us from outer space; and holds moisture (clouds), gases, and tiny particles. In short, the atmosphere is the protective bubble we live in.

This protective bubble consists of several gases (listed in the table to the right) with the top four making up 99.998% of all gases. Of the dry composition of the atmosphere nitrogen, by far, is the most common. Nitrogen dilutes oxygen and prevents rapid burning at the Earth's surface. Living things need it to make proteins. Oxygen is used by all living things and is essential for respiration. It is also necessary for combustion or burning. Argon is used in light bulbs, in double-pane windows, and to preserve the original Declaration of Independence and the Constitution. Plants use carbon dioxide to make oxygen. Carbon dioxide also acts as a blanket that prevents the escape of heat into outer space. These percentages of atmospheric gases are for a completely dry atmosphere. The atmosphere is rarely, if ever, dry. Water vapor (water in a 'gas' state) is nearly always present up to about 4% of the total volume. In the Earth's desert regions (30°N/S) when dry winds are blowing, the water vapor contribution to the composition of the atmosphere will be near zero. Water vapor contribution climbs to near 3% on extremely hot/humid days.

The upper limit, approaching 4%, is found in tropical climates. The table below shows the changes in atmospheric composition with the inclusion of different amounts of water vapor. The earth's atmosphere is a very thin layer wrapped around a very large planet. Two gases make up the bulk of the earth's atmosphere: nitrogen ( ), which comprises 78% of the atmosphere, and oxygen ( ), which accounts for 21%. Various trace gases make up the remainder. Based on temperature, the atmosphere is divided into four layers: the troposphere, stratosphere, mesosphere, and thermosphere. Energy is transferred between the earth's surface and the atmosphere via conduction, convection, and radiation. Ocean currents play a significant role in transferring this heat poleward. Major currents, such as the northward flowing Gulf Stream, transport tremendous amounts of heat poleward and contribute to the development of many types of weather phenomena. Cambridge University Graphic The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space. 1) The troposphere is the first layer above the surface and contains 70 to 80 per cent of the Earth's atmosphere. Weather occurs in this layer.

2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun. 3) Meteors or rock fragments burn up in the mesosphere. 4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits. 5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere. National Geographic Video U.S. Weather Service Graphic The inhabitants of our planet live in the Troposphere. Earth's atmosphere varies in density and composition as the altitude increases above the surface. The lowest part of the atmosphere is called the troposphere (and it extends from the surface up to about 10 km (6 miles). The gases in this region are predominantly molecular Oxygen ( O2 ) and molecular Nitrogen ( N2 ). All weather is confined to this lower region and it contains 70 to 80 per cent of the Earth's atmosphere and 99% of the water vapor. The highest mountains are still within the troposphere and all of our normal day-to-day activities occur here. The high altitude jet stream is found near the tropopause at the the upper end of this region.

The layer above this is the Stratosphere, this is where the Ozone Layer is formed. The atmosphere above 10 km is called the stratosphere. The gas is still dense enough that hot air balloons can ascend to altitudes of 15 - 20 km and Helium balloons to nearly 35 km, but the air thins rapidly and the gas composition changes slightly as the altitude increases. Within the stratosphere, incoming solar radiation at wavelengths below 240 nm. is able to break up (or dissociate) molecular Oxygen ( O2 ) into individual Oxygen atoms, each of which, in turn, may combine with an Oxygen molecule ( O2 ), to form ozone, a molecule of Oxygen consisting of three Oxygen atoms ( O3 ). This gas reaches a peak density of a few parts per million at an altitude of about 25 km (16 miles). The Ozone Layer absorbs ultra-violet radiation from the Sun. Without the Ozone Layer life as we know would cease to exist on our planet. Ozone is important because it is the only atmospheric gas which absorbs light in the B region of UVB rays.

The Ozone layer extends from a height of 20 kilometers to 60 kilometers above the Earth's surface. The air is very thin at these altitudes. If all of the Ozone in the Earth's atmosphere were compressed into a single layer at the Earth's surface, it would only be 3 millimeters thick-basically two stacked pennies! The gas becomes increasingly rarefied at higher altitudes. At heights of 80 km (50 miles), the gas is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive ion. The existence of charged particles at this altitude and above, signals the beginning of the ionosphere a region having the properties of a gas and of a plasma.

Question: In which layer of the atmosphere would you find "The Ozone Layer?
Answer: Stratosphere